Demonstrate how a fuse protect an appliance from excess current flow

Suitable For

Grade 5

Difficulty

1

Time Required

<2 Days

Supervision

Advised

What’s it about?

An electrical ‘short’ can cause an excess amount of current to be drawn from a power source. A ‘short’ happens when the normal ‘resistance’ of an electrical circuit falls so that it has less ‘resistance’ than normal, such as when an electrical component fails.

Household appliances such as electric heaters or hairdryers draw a large amount of current during operation, and when a ‘short’ occurs in such an appliance, an excess amount can be drawn from the power socket causing so much heat in the wires that it can result in a fire!

A ‘fuse’ is used to prevent an appliance from drawing too much current and is also used in electrical panels to protect the wiring in homes from overheating. Make a simple fuse in the following science experiment to learn how they operate:

Topics covered

Fuse, Short circuit

What will I need?

INSULATED COPPER WIRE

9-VOLT BATTERY

9-VOLT LIGHT BULB

WIRE CUTTERS

SWITCH

STYROFOAM BOARD

DRAWING PINS

ALUMINIUM FOIL

SCISSORS

SCREWDRIVER

Procedure (Method)

Unfortunately, this section is only available in the e-book version of the project.

How does it work?

Unfortunately, this section is only available in the e-book version of the project.

In this science experiment, placing a screw driver across the bare wires caused a ‘short circuit’, because the aluminium strip which serves as the fuse, heats up, melts off and breaks the circuit and flow of electricity. A ‘short circuit’ occurs when a metallic wire or a metallic object is placed between the bare wires or contacts of the battery. This causes electricity to flow without any resistance. Due to the reduced resistance, a large amount of electricity flows, producing a lot of heat that melts off the thin aluminium foil strip. The materials used for a ‘fuse’ must be a good ‘conductor’ but also have a low melting point.

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